Juan Battle and Earl Wright II published W. E. B. Du Bois's Talented Tenth: A Quantitative Assessment in the Journal of Black Studies, 32:6 (2002):654-672. It can be downloaded from Dr. Wright's web site as a PDF file.
In the United States, the size of parking spaces varies. Typically they fall between 7.5 to 9 feet wide and 10 to 20 feet long. The most common size is 8.5 feet wide by 19 feet long.
Estimate the area per parking stall that is appropriate for the site. Typical ranges for surface parking lots are 300 to 350 square feet per parking stall, which includes the area required for the parking stall and drive aisles. Oddly configured sites, such as those with unusual shapes, or narrow sites are more difficult to use efficiently for parking, and the land area required per stall will be higher.